Hypoxia has long been known to be a factor in tumor resistance to radiation therapy. A correlation between hypoxia and radiation resistance in patients wit cancers of the head and neck has recently been documented using pO2 electrodes. We have developed state-of-the-art methods to obtain metabolic information in vivo using 31P magnetic resonance spectroscopy (MRS), and this has provided us new insights into the in vivo biochemistry of various human cancers. In this Project, we will take advantage of this unique combination of methods, to study the relation between hypoxia and metabolic characteristics of cancers of the head and neck. We will obtain multiple pO2 measurements from the cancers using the microelectrode histograph. The quantitative measures of hypoxia obtained will be correlated with metabolic status of the cancers measured using proton-decoupled 31P MRS with coils designed by the Instrument Core. In particular, we will test three hypotheses: Hypothesis I B that 1H-decoupled, NOE-enhanced 31P MRS techniques developed at the FCCC for human lymphomas, sarcomas and breast cancers will also yield important metabolic characteristics of squamous cell carcinomas of the head and neck. Hypothesis II B that pretreatment tumor oxygenation parameters measured by Eppendorf pO2 microelectrodes correlate directly with tumor metabolic characteristics defined by 31P MRS spectra of the same tumors. Hypothesis III B That tumor oxygenation status determined by microelectrodes prior to therapy and/or treatment-induced changes in 31P MRS spectra will be predictive for tumor treatment response. The information obtained in this Project will be an important addition to our understanding of hypoxia in this class of human tumor and how it relates to 31P MRS parameters as well as how they both relate to treatment response.